Her comments came just two days ahead of the second anniversary of Mrs Merkel announcing all Syrian asylum seekers are welcome to remain in Germany, regardless of which European Union country they had first set foot in.

The announcement meant Germany became the first state in the 28-member bloc to suspend the 1990 Dublin Regulation, which forces refugees to seek asylum in the first country they enter.

And her decision was widely criticised by many within Germany and across the continent, as Mrs Merkel faced accusations of contributing to the migrant crisis with her open door policy.

Several anti-immigration protestors at Mrs Merkel’s rally at Bergisch-Gladbach on Tuesday made it clear they had not forgotten the controversial policy.

PA

Angela Merkel addresses an election campaign rally

A group of right-wing Alternative for Germany (AfD) protested loudly with whistles as they disturbed the Chancellor's speech with loud boos and shouts of "get lost!".

The CDU election campaign team are well used to boos during their tour of Germany a month before the Spetember 24 election.

The rally was hijacked by a crowd of protestors from the right-wing Alternative for Germany (AfD) and the anti-migrant Pegida movement.

More than 150 protestors descended on the rally chanting "not my chancellor", as they waved banners reading "get out of here" and "traitor to the nation".

The group also held signs reading "regime change in Germany" and "CDU - we are destroying Germany".

One month before voters go to the ballot box, the left-leaning Social Democratic Party (SPD) is languishing on around 24 percent support, polls show - far behind Merkel's conservatives bloc, on some 38 percent